Measurements are reported on the magnetization reversal in submicron magnetic rings fabricated by high-resolution electron beam lithography and lift-off from Cobalt thin films. For all dimensions investigated, with diameters of 300 nm-800 nm and a thickness of 10 nm-50 nm, the flux closure state (FC) is the stable magnetization configuration. However, with increasing diameter and decreasing film thickness a metastable near single domain state (SD)

The possible magnetization configurations of individual circular Co(0001) dots are investigated by means of 3D micromagnetic simulations as a function of dot dimensions. In zero applied field, the vortex state corresponds to the ground state for diameters larger than 60 nm and up to a thickness of 25 nm where a transition into a weak stripe structure occurs.